The present invention relates to communications systems; more particularly, the invention relates to circuits for fault isolation on a communications system wherein system interconnections are made by way of a single twisted pair wiring loop. Such communications systems are well known in the prior art, wherein a plurality of communications nodes are dispersed along a twisted pair signal loop, the ends of the wiring loop being connected to a computer processor or like device. Unless particular precautions are made, an open circuit or short circuit at any point along the loop will usually cause a communications failure between the processor and all systems connected to nodes along the loop.
Different fault isolation and/or correction techniques are typically utilized in situations wherein the fault is caused by an open circuit versus situations wherein the fault is caused by a short circuit along the communications loop. Whereas there are a number of prior art techniques for fault isolation wherein the fault is caused by an open loop, it is more difficult to maintain communications line integrity and fault isolation in situations where communications loops are short circuited at some point along the loop.